1. Field of the Invention
The present invention relates to methods and apparatus for continuously fabricating corrugated board from web materials. More particularly, the present invention relates to a jig for accurately setting stripper fingers and the like on web corrugating machines.
2. Description of the Prior Art
By the prior art technique of fabricating corrugated board from webs of paper, as illustrated by FIG. 1 of the Drawing, a continuous web W is delivered into the meshing nip 50 between two corrugating rolls 51 and 52. The periphery of these corrugating rolls comprises an undulating surface of longitudinally extended flutes. Such flutes mesh together as gears when the rolls are rotatively driven.
Upon emergence from the meshing nip, the undulated web which is to form the sinusoidal medium between two face laminae of finished, double-face board, is held tightly against one of the corrugating rolls for approximately 180.degree. of roll arc into a second nip 54 with a smooth surface roll 53 which presses a flat web of first liner sheet L into adhesive contact with the flute tips of the undulating medium. To positively control the medium course from the corrugating nip to the liner nip, a multiplicity of crescent shaped fingers 20 are provided. These fingers project into the corrugating roll nip 50 within circumferential slots cut across the fluted surface of one such roll 51. The projected nip point 22 of such fingers strips the emerging web from the surface of said one corrugating roll and provide, by the arcuate internal edge 21 of each finger, a channel to confine the corrugated medium against the undulated surface of the other corrugating roll 52.
To perform the stripping and guiding function properly, the said fingers must be rigidly secured on a finger mounting bar 55 in a position spaced from the cooperative corrugating roll flute tips at a distance equal to the thickness of the medium web plus approximately 0.001 to 0.002 inch. Normally, this spacing adds to about 0.010 inch, total. Moreover, such clearance must be uniform over the full arcuate length of the finger.
Such close tolerance positionment of the fingers creates operational difficulty when it is further considered that there are approximately 30 fingers on a machine of normal, 87 inch width web capacity equally spaced on 3 inch centers. Furthermore, such fingers are fabricated of brass and are easily and frequently distorted by disturbances in the medium flow. These circumstances, therefore, are the source of considerable, non-productive downtime.
In the past, to expedite the finger setting task, such fingers were secured by cooperative holders 30 on a jig having a cross-sectional or wafer portion of the subject corrugation roll secured to a jig frame. Such a jig has mounting holes by which the finger holder is secured to the jig frame in exactly the same position relative to the corrugating roll axis as the finger-holder unit assembly would have on the subject machine. This technique permits the fingers to be relatively quickly and conveniently combined with a respective holder in the exact location relative to the roll that the unit would have on the subject machine. When removed from the jig and secured to the finger mounting bar on the subject machine, the precise finger position has already been determined.
So long as the original roll wafer accurately represents the size and configuration of the cooperative corrugating roll, the aforedescribed jig setting technique performs quite well. However, if the roll is subsequently re-machined due to wear and scratches in the fluted surface thereof, the said prior art jig is rendered useless due to lack of correspondence between the jib wafer and the actual roll. Consequently, either another jig wafer must be made to accurately copy the new roll profile or all fingers must be repetitively set in place to the required clearance on the actual machine.
It is therefore, an object of the present invention to teach the construction of a novel finger setting jig having radially adjustable reference surfaces whereby the exact profile of any roll may be simulated as a reference surface for securing a finger-holder unit in the required relationship which provides the required clearance space when secured to the finger mounting bar.